W.F. Zhang

Room-temperature ferromagnetism in Cu-implanted 6H-SiC single crystal

200u2009keV Cu+ ions were implanted into 6H-SiC single crystal at room temperature with fluence of 8u2009×u20091015u2009cm−2. No ferromagnetism (FM)-related secondary phase was found by the results of high-resolution x-ray diffraction and x-ray photoelectron spectroscopy. Positron annihilation lifetime spectroscopy results indicated that the main defect type was silicon vacancy and the concentration of it increased after Cu implantation. The room-temperature ferromagnetism was detected by superconducting quantum interference device. First-principles calculations revealed that the magnetic moments mainly come from the 2p orbitals of C atoms and 3d orbitals of Cu dopant. The origin of the FM has been discussed in detail.

Photovoltaic enhancement by Au surface-plasmon effect for La doped BiFeO3 films

Herein, the photovoltaic (PV) effect of ferroelectric Bi0.85La0.15FeO3 (BLFO) films fabricated through a sol–gel method is investigated. The ferroelectric properties of the BLFO films improve compared to the undoped BiFeO3 films. The application of Au nanoparticles (AuNPs) increases the open circuit voltage (VOC) and short circuit current density (JSC) from 0.2 V to 0.3 V and 5.3 μA cm−2 to 18.5 μA cm−2, respectively, which could be attributed to Au surface-plasmon effects. The PV output for the BLFO film can be modulated after applying external poling voltages. Considering the ferroelectric polarization and plasmonic effects, a plausible theoretical model is constructed to depict the physical mechanism of PV enhancement for the BLFO film in detail. This work not only presents a new approach to improve the PV effect of ferroelectric films but also provides important insights into the PV mechanism of ferroelectric films.

Electrodeposition and low-temperature post-treatment of nanocrystalline SnO 2 films for flexible dye-sensitized solar cells

SnO2 porous films were electrodeposited on Ti substrate using pulse-potential technique. These deposited films were dealt with different post-treatments. The effects of the post treatments were investigated through X-ray diffraction, FE-SEM, and Raman spectra. These investigations showed that crystal nanoporous SnO2 films were obtained through low-temperature post-treatment process. The photoelectric conversion efficiency of the SnO2 film treated with both the water vapour treatment and ultraviolet illumination was improved to be 0.35% which was comparable with the conversion efficiency of the film sintered at 550°C.